Getting that "Jump" sound

I've been trying for a while to achieve the sound of an Oberheim OB-Xa on the XP-80, and nothing I try - effects, cutoff, high-speed saw LFOs - works at all. Everything sounds thin, cheezy, and digital. I even used White Noise as one of the tones, and I still can't get that sort of warm, fat, gritty sound you can hear in a real OB-Xa. Anybody got any ideas?

I have the Vintage Synth expansion board, by the way.

The quickest way to create the sound need is by starting with a preset that is at least close to what you are looking for. The "Jump" sound is in the synth brass category. So audition some of your synth brass type presets then when you find one that is close to the sort of sound for playing the "Jump" line, and then tweak the synth parameters until you the tone you are looking for. Apart from saving you a lot of time you will also learn by learning from existing patches and the tweaking will give you a feel for what each of the parameters do.